Abou Diaby’s own goal consigned Arsenal to their first defeat of the season at Old Trafford on Saturday evening.

The Frenchman midfielder inadvertently nodded home a Ryan Giggs free-kick in the 64th minute to complete Manchester United’s second-half comeback on a disappointing day in the North-West.

Arsenal had looked good value for their lead until the 59th minute when Manuel Almunia clipped Wayne Rooney in the area and the England striker scored from the spot.

Andrey Arshavin’s thunderous drive had given the visitors the advantage five minutes before the interval and, just after the restart, keeper Ben Foster saved point-blank from Robin van Persie.

This was a decent performance from Arsenal but the key moments in the second half did not go their way.

This game was never going to be decisive in Premier League terms but it was an illuminating yardstick for both sides at the start of the campaign,

Manchester United took the spoils but Arsenal showed enough to suggest they will be a force this season.

Wenger opted to make two changes for the first “Big Four” clash of the Premier League campaign. Nicklas Bendtner and Eduardo dropped out from side that beat Celtic in midweek. Van Persie and Arshavin came in.

With Cesc Fabregas (hamstring) injured Diaby, Denilson and Alex Song formed the midfield three while Willam Gallas and Thomas Vermaelen were paired at centre back.

Before kick-off, victories for Chelsea and Tottenham had put them joint top with 12 points. Both of these sides began this game with just six. A defeat for either would be far from terminal in terms of the title race but it would certainly make the table unhappy reading in until the Premier League kicked off again in a fortnight’s time.

Arsenal started brightly but had created little before hesitancy at the back saw Darren Fletcher hook the ball from close range in the ninth minute.

The home side then started to pressure and, on the quarter-hour, William Gallas’ miskick allowed Nani to go clear and only a superb challenge from Bacary Sagna stopped the Portuguese going clear on the left.

The game was starting to open up. In the 22nd minute, Patrice Evra reached the byline and whipped the ball back to the near post where Vermalen shepherded Rooney out of the way. Arsenal broke immediately and suddenly Van Persie was in the area. The Dutchman pirouetted to get the ball on his left foot however Evra had raced back and deflected the resulting shot high over the bar.

Van Persie took the corner himself and keeper Ben Foster could only slap the ball out to Arshavin 15 yards out. His rising sidefoot shot whistled a whisker wide of the far post. Arsenal’s closest effort so far.Manchester United continued to have more pressure. Gallas clipped Evra as he burst through and Rooney curled the free-kick wide.

But Arsenal had a couple of credible shouts for a penalty before they would took the lead. Van Persie was clipped on the right of the area and then, more obviously, Darren Fletcher clattered into Arshavin a minute or so later. Both times referee Mike Dean waved play on.

The Russian would have swift revenge.

Five minutes from half time, Arshavin collected the ball on the left and unleashed one of his, now trademark, thunderbolts. It was too powerful for Foster, who could only palm the ball into the top corner of the net.

Manchester United were stung. They had edged the first half until then and tried to restored parity before the break. The closest they came was when Nemanja Vidic saw his shot kicked off the line following a corner from Giggs

By the time the second half had begun, rain had arrived in Manchester.

The home goal was also under a bit of a deluge as the game restarted. Arshavin’s burst of pace saw him beat Vidic to the byline and cross low for Van Persie in the six-yard area. The Dutch striker got away his shot first time but Foster flicked out a foot to divert the ball wide from point-blank range.

Seconds later, an unmarked Eboue miscontrolled Clichy’s cross at the far post when he should have tried his luck with a volley.

Antonio Valencia blazed over as Manchester United started the claw their way back into the game. They would not have to wait long for an equaliser. In the 59th minute, Rooney raced across the area and poked the ball away from Almunia. The keeper certainly made contact with the striker as he went through. Rooney picked himself up and stroked the ball home from the spot.

Arsenal nearly produced a sucker-punch two minutes later when Van Persie whipped in a free-kick from the right, Foster misjudged it and the ball bounced off the bar.

However Manchester United took the lead shortly afterwards in bizarre fashion. In the 64th minute Giggs curled in a free-kick to the near post and, under little pressure, Diaby nodded the ball into his own net.

Evra forced a low save from Almunia as Manchester United looked for a third. With 19 minutes left, Wenger withdrew Eboue for Bendtner as he pushed on for an equaliser.

The change produced pressure but no real chances. Vermaelen sent a header wide while Diaby and substitute Eduardo tried to be a danger in the Manchester United area.

In fact it was the home side that had all the opportunities. Another replacement, Dimitar Berbatov sliced horribly wide then, in injury time, Nani wasted two chances.

In the final seconds, Van Persie slammed home from six yards but in the build-up, Gallas had been flagged offside. Following that, Wenger was sent from the dug-out by referee Dean.